Turbine Disc Thermal Stress Reduction via Pre-Heating
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Solution Overview
Problem
Aircraft gas turbine engines face significant challenges in maintaining longevity due to crack propagation in turbine discs and other rotating components, primarily caused by thermal stresses resulting from uneven temperature gradients during engine acceleration and deceleration.
Innovation Solution
Implementing a control system that uses electrical heating devices, such as resistive or inductive heaters, to gradually increase the temperature of turbine discs before and during engine acceleration or deceleration events, thereby reducing thermal gradients and stresses by distributing heat evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine operates through rapid acceleration or deceleration events, then power response and operational flexibility are improved, but temperature gradients and thermal stresses in turbine discs increase rapidly
Solution Approach 1:
The control system performs preliminary heating of the turbine disc before an acceleration event occurs. By detecting upcoming acceleration or deceleration events and applying heat in advance, the system prepares the disc to accommodate thermal changes more gradually, reducing thermal stress during the actual event while maintaining the ability to respond quickly when needed.
Solution Approach 2:
The system dynamically changes the temperature parameter of the turbine disc by applying electrical heating. This controlled parameter change allows the disc temperature to be adjusted in advance, creating a more favorable thermal state that reduces stress during subsequent rapid operational changes.
2Duration of action of stationary object
If electrical heating devices are applied to the turbine disc in advance, then thermal stresses are reduced and disc life is extended, but device complexity and energy consumption increase
Solution Approach 1:
The control system monitors engine operational parameters and automatically determines when heating is required, eliminating the need for manual intervention. The system serves itself by detecting upcoming acceleration events and independently activating the heating devices at the appropriate times, reducing operational complexity while extending disc life.
Solution Approach 2:
The system uses feedback from engine operational data to control the heating devices. By continuously monitoring parameters such as current temperature, acceleration rates, and flight conditions, the control system adjusts heating application in real-time, optimizing disc protection while managing energy consumption and system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach extends the life of turbine discs and consequently the entire engine by minimizing crack formation and propagation, as the controlled heating reduces thermal stresses and promotes more uniform temperature distribution.
Implementation Method 1
The electrical heating device may comprise a resistance heater configured to convert electrical energy to thermal energy
Implementation Method 2
The electrical heating device may comprise an induction heater configured to convert electromagnetic energy to thermal energy
Implementation Method 3
A first cooling airflow is provided to a bore of the disc and a second cooling airflow is provided to a rim of the disc
Data Source
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AI summary
A gas turbine (10) engine and method of operation. The gas turbine engine (10) comprises a heating device configured to heat a rotor disc (32, 72) of the engine (10). A method of operation the heating device comprises detecting an engine acceleration or deceleration event, or determining that an engine acceleration or deceleration event is imminent or may be imminent. On detection of an engine acceleration or deceleration event, or in advance of the engine acceleration or deceleration event, increasing turbine rotor disc heat input to raise a temperature of the turbine rotor disc or reduce a cooling rate of the rotor disc.